Dementia will affect most dogs if they live long enough

As dogs age, their brains undergo decline, just as happens with humans. This can lead to the condition known as canine cognitive dysfunction (CCD), which is characterized by changes in awareness and behaviour, and a gradual loss in the ability to remember or learn new things. It is a common disorder among senior dogs, with around one out of every three dogs over the age of 11 showing at least one clinical sign of the condition. By the age of 16, almost all dogs suffer from aspects of this doggy dementia.

Sadly, a great number of owners fail to discuss behavior changes in their geriatric dog with a veterinarian because they assume that these problems are a natural and untreatable aspect of aging. However, the neurodegenerative changes that occur in an older dog’s brain are progressive in nature, meaning that the sooner they are detected, the more effectively they can be corrected or, at least, slowed down.  

Sarah Yarborough from the University of Washington, and colleagues, have now conducted new research into the prevalence of CCD in a large sample of companion dogs. The owners were all participants in the Dog Aging Project, a longitudinal study of aging in pet dogs in the USA. A total of 15,019 dogs were included in the sample and they were categorized according to their positions along their lifespans. A total of 20 percent of the dogs were in the last quartile of their life, 24 percent were in the third quartile, and 27 and 29 percent were in the second and first quartiles respectively.

Between December 2019 and 2020, the pet owners completed two surveys called the Health and Life Experience Survey (with information about health status and physical activity), and the Canine Social and Learned Behavior survey, which included questions to test for the presence of CCD symptoms, such as whether the dog failed to recognize familiar people or showed loss of memory. The data from these surveys indicated that 1.4 percent of dogs were classified as having CCD.

Published in the journal Scientific Reports, the study revealed that when considering age alone, the odds of a dog being diagnosed with CCD increase by 68 percent for each additional year they live beyond the age of ten. When other factors such as health problems, sterilization, activity levels, and breed type were taken into account, the odds of developing CCD increased by 52 percent for each additional year of life over the age of ten.

The researchers also noted that for dogs of the same breed, age, and health and sterilization status, the odds of CCD were 6.5 times higher in dogs that were reported by their owners as being inactive, in comparison with dogs that were reported to be active. However, the experts caution that their study does not show a causal relationship between inactivity and CCD due to its cross-sectional nature, and cognitive decline may be the factor leading to reduced activity. 

The researchers suggest that lifespan estimates could help inform veterinarians whether to screen dogs for CCD when they are brought in for other health checks. They also conclude that further research is needed to understand CCD better.

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By Alison Bosman, Earth.com Staff Writer